The specific aim of the proposed research is to provide basic data which will allow an evaluation of the adequacy of the conditioning theory of psychopathology. This theory has been criticized on the grounds that the fear underlying neurotic behavior is extremely persistent and does not extinguish readily, unlike the fears conditioned in the laboratory. A number of conditioning processes that could account for the maintenance of fear and, hence, of neurotic behavior will be investigated. These include reinstatement or reconditioning of extinguished fear, the increase in the stimulus generalization of fear with time, and the conditioning of fear to compound stimuli. The effect of the depth of extinction on the reinstatement of extinguished fear will also be studied. A hurdle-jumping, escape-from-fear task, which allows a clear separation between the conditioning of fear and the effect of such fear on instrumental learning, will be employed using rats as subjects.